MONTREUX, Switzerland (AP) -- As senior U.S. and Iranian officials worked in Switzerland Tuesday to reach a nuclear deal, Israel's leader warned against reaching an accommodation with Tehran, declaring to the U.S. Congress that Tehran aims for Mideast dominance and won't let any such pact thwart its plan.

The negotiations, being led by Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif, have less than a month to go to meet a late-March deadline for a pact meant to crimp Iran's nuclear program in exchange for sanctions relief. But even as the two sides met in a luxury hotel in the Swiss resort town of Montreaux, Israeli Prime Minister Benjamin Netanyahu was making his case against their slowly emerging agreement 4,090 miles (6,500 kilometers) away in Washington.

Instead of depriving Tehran of the means to make nuclear arms, the deal being negotiated "would all but guarantee that Iran gets those weapons, lots of them," by leaving much of Iran's nuclear infrastructure intact, Netanyahu told the joint houses of Congress, in a 40-minute speech frequently interrupted by standing ovations.

In a sign that Netanyahu's speech was resonating outside Washington, Zarif decried comments that President Barack Obama made on Monday - as part of an administration-wide effort to push back on the Israeli's criticism - in which he said that Iran would have to suspend its nuclear activities for at least a decade as part of any final agreement.

Zarif, in a statement quoted by Iran's official news agency IRNA, said Obama's remarks were "unacceptable and threatening," aimed at attracting U.S. public opinion while reacting to Netanyahu "and other extremist opponents of the talks."

The U.S. and Iranian sides met for two hours on Tuesday morning before taking a break, according to U.S. officials. The officials said earlier they expected the talks would resume and likely continue through Netanyahu's address to Congress, delivered in the late afternoon local time in Montreux.

"We're working away, productively," Kerry told reporters.

"We are moving and we are talking to be able to make progress," Zarif said. "There are issues and we want to address them. But there is a seriousness that we need to move forward. As we have said all along, we need the necessary political will to understand that the only way to move forward is to negotiate."

The U.S., Iran and other world powers are racing to meet the end-of-March target to reach the outline of deal, with a July deadline for a final agreement.